Process for making amines



,foilowing invention which comprises subjecting 10 otherwise stated parts are by weight.

Patented Dec. 14, 1948 'NITED STATES aren't orrc raoonss FOR MAKING AMINES William W. Prichard, Claymont; Dell, ,assignor to E. I. du Pont de Nemours &. Company, Wilmington, Del, a corporationof Delaware No Drawing. Application February 27, 1946,

Serial No. 650,737

Claims. (Cl-QfiO-r-563.) 1 2 This invention relates to hydrogenation proc- I Example II esses, and more particularly to the production of Fifty par-ts of hexahydmbenzyndene diacetate,

amines by Said processesas arts or rrethanol 35 rt f t 1 An object of this invention is a new method for 5 flirts of g :3 F 2 g 32:32

the preparation of amines. Another object is a 5 o a catalytic method of converting carboxylic acid di- 222. a :9 2009 hy r L pressure for 4 hours. At the end of this time esters of 1,1-glycols to amines. Other ob ects are the product is discharged the catalyst is Sam to advance the 1 rated by filtration and the methanol removed by The above ObJects are accomphshed by the distillation atatmospheric pressure. The viscous residue obtained is made strongly alkaline with sodium hydroxide solution and steam distilled. The'steam distillate is extracted with ether and the other solution is treated with 10% hydroohiorio acid to remove the basic constituents. The amine is liberated from the aqueous acid solution'by addition of sodium hydroxide, dried over anhydrous sodium'sulfate, and distilled. There a carboxylic acid diester of a 1,1-glycol to the action of hydrogen in the presence of at least one mole of a substance of the class of ammonia and primary and secondary amines per mole of diester, and a hydrogenation catalyst.

In one preferred embodiment, a reactor is charged with the-mentioned diester and an equal W of methanol as q To thls charge is obtained-30 parts of N-ethyl hexahydrobenzyls added about 2%, by weight of the mentioned amine boiling at 9L9 C /37 mm diester, of a hydrogenation catalyst selected from group VIII of the periodic table and at least one Example III mole of anhydrous ammonia per mole of the carf r I a r ,1. ypaits of hexahydrobenzyhdene diacetate,

poxyhc vacld Chester of The leactor 5 parts of alloy-skeleton nickel catalyst, 50 parts is placed on an agltatmg rack pres of diethylamine, and 80 parts of methanol are fured hydtogen to at least t chargedinto a 400 cc. stainless steel reactor and reactlon mlxture heated to a temperature m hydrogenated at2000 Ila/sq. in. hydrogen pressure the range of 50 to 200 After hydrogen at 85 C. for 3 hours. After discharging the conabsorptlon ceases the reactor 1s cooled, opened, terns the reactor the catalyst is removed by and the contents'dischgrged fi1tered.t filtration and the methanol is removed. by dismove the catalyst The reaction product 15 tiilationzat atmospheric pressure. Fifty parts of arated from the methanol and excess ammonia, 40% sadium r a ydroxide is added to the residue treated with alkali to liberate the amine, and the and ma alkaline solution is Steam distilled amine recovered by distillation or by other means There is thus obtained, 34 parts of d1 ethy1 knOWn the a hexahydrobenzylamine, B. P, 101 -104 0 37 mm.

The examples, which follow are illustrative of ND2 5 1. 4564,6

methods for practicing the invention Unless Although in the above examples there have been used certain conditions of. temperature and Example I pressure, concentration, duration of reaction, etc, ex h d b M Ede ,dia at te it. is to be understood that these values may be 5 g; ifi g gf g i z i 3 metgmgol, 40 varied somewhat within the scope or" the inand 20 parts of ammonia are charged into a Ventlon' 400 cc. stainless steel reactor and hydrogenated In geneliahthe 1S Operable at tempera under. 2000 lb./sq. in. hydrogen pressure at 100 C. e s e from Q to about AS rule: for i'hours. At the end of this time theproduct the fi 1S p ated at temperatures inthe is discharged and the Catalyst xrmbved by range: 60? to 125*" C..s1nc.e under these conditions tration. The solvent is removed by distillation at the ma takes place f f' with atmospheric pressure, the excess ammonia being the production of the desired amines in maximum vaporized concurrently. The residual product is 3719165 distilled to give 29'parts of hexahydrobenzylam- "Hydrogenation carried Out at pressures in monium acetate, 3 7.4 7 C. excess of atmospheric. Forbest results pressures An alternative method for isolation or the which min excess of d generally in omprjs s Removal f e y m t in excess of 300 Ila/sq. in. are used slnce under lation, addition of excess aqueou alkali t t such conditions satisfactory reaction rates are residue to neutralize the acetic acid liberated in obtalnefl- The upper pres-911m 111111173 i cv f the hydrcgenolysis, and then steam-distillation of determined only by the structural limitations or the alkaline solution to recover the amine. the equipment mp oyed. I Twenty-eight parts of hexahydrobenzylamine is The process y be Out in the absence obtained in this Way. The hexahydrobenzylof a solvent, but it is generally operated in the amine has the following constants: E. P., (Sipresence of an organic solvent such as an alcohol, C./25 mm, d4 =0.8682, n =1.4579. ether, or hydrocarbon. Examples of specific,

operable, organic solvents are methanol, ethanol, propanol, isopropanol, dioxane, cyclohexane, etc.

The amount of catalyst used depends upon the activity of the catalyst. In general, the amount of catalyst used is that needed to bring about reaction at a suitable rate under the temperature metals, chromium, manganese, aluminum, thorium or magnesium. The catalyst may be employed in massive form or in finely divided form on suitable carriers such as kieselguhr and the like. I i

As previously stated, particularly useful catalysts are metallic iron, nickel, and cobalt. These maybe used in their pyrophoric or stabilized forms. Pyrophoric catalysts can be prepared by any method giving an active form of the metal.

,These pyrophoric metal catalysts may be supported or unsupported, and maybe made by reducing an oxide, hydroxide, or reducible salt of iron, nickel, or cobalt with hydrogen at a relatively high temperature, the metal not being exposed to an oxidizing atmosphere prior to use. These pyrophoric metals may be stabilized by exposure to an oxidizing atmosphere, while main- .taining the temperature of the catalyst mass below C. v The process of this invention may be effected as a liquid or vapor phase operation. It may be also efiected as a batch, semi-continuous, or continuous operation.

Although the process is most useful in the preparation of primary amines from carboxylic acid diesters of 1,1-g1ycols and ammonia it may also be used in the preparation of secondary and tertiary amines by employing suitable primary or secondary amines in the hydrogenation in place of ammonia. Suitable examples of such amines are methyl, ethyl, propyl, butyl, amyl, octyl, and decyl amines, diethylamine, diamylamine, dioctylamine, methyl decylamine, octadecyldecylamine, didodecadecylamine, 1,2-diaminoethane, 1,6-diamiuohexane, 1,8-diaminooctane, aniline, cyclohexylamine, p,p-diaminodiphenyl, p,p'-diaminodicyclohexyl, piperidine, and the like.

The amount of ammonia or primary or secondary amine used should be at least one mole per mole of the carboxylic acid diester of a 1,1-glycol. It is generally desirable, however, to use an excess of ammonia or primary or secondary amine ranging from 1 /2 to 100 molesper mole of the diester. In place of the specific diester of the examples, there can be used other carboxylic acid diesters of 1,1-g1ycols having the general formula wherein R and R are hydrocarbon radicals of the class of aliphatic, aromatic, and cycloaliphatic radicals. Specific examples of compounds operable in the practice of this invention are methylidene, ethylidene, propylidene, isopropylidene, and dodecylidene diactates, dipropionates or dibenzoates, benzylidene and xylylidene diacetates, cyclic esters such as ethylidene succinate or hexahydrobenzylidene phthalate.

As many apparently widely different embodiments of this invention may be made Without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

I claim:

l; A process for making amines which compiises heating at a temperature of from 50 C.

to 200C. in contact with hydrogen under a pressure of at least pounds per square inch and a hydrogenation catalyst a carboxylic acid diester of a 1,1-glycol and at least one mole per mole of diester of a substance selected from the group consisting of ammonia, primary amines,

and secondary amines, the amino group in said amines being the sole functional group contained therein.

2. A process for making amines which comprises heating at a temperature of from 50 C.

to 200 C. under a pressure of at least 100 pounds per square inch hydrogen, a hydrogenation catalyst selected from Group VIII of the Periodic Table, a carboxylic acid diester of a 1,1-glycol, and at least one mole per mole of diester oi a substance selectedfrom the group consisting of ammonia, primary amines and secondary amines, the amino group in said amines being the sole functional group contained therein, said diester being of the generalformula REFERENCES CITED The followingreferences are of record in the ,fileof this patent:

UNITED. STATES PATENTS Number Name Date 2,116,971. Schmidt July 25, 1939 FOREIGN PATENTS Number V Country Date 599,103 'Germany Sept. 15, 1932 France May 25, 1935 

